The Los Angeles Police Department says two suspects opened fire on a patrol car with a rifle Sunday evening.
"Several rounds were shot in the direction of the officers, LAPD Capt. Lillian Carranza said.
"'This was a completely unprovoked attack,' she added.
"One of the officers returned fire toward the alleged gunmen, but it was not immediately clear whether either was hit."
The two officers inside the car survived without injuries and one of the suspects was apprehended. But the search for the other suspect resulted in a manhunt through the evening.
"Police recovered a rifle at the scene of the shooting, which occurred about 9:30 p.m.
"A three-block area around the shooting scene was immediately cordoned off after the attack as police scoured the area with search dogs.
"Just before 11 p.m. LAPD advised residents to stay indoors. 'Armed suspect in the area,' the police station said on Facebook. 'Please keep our officers in your thoughts and prayers!'"
Police departments across the country have been on alert after a gunman shot and killed two New York City Police officers more than a week ago.
There is no word on motive for the attack in Los Angeles.